Lithium manganese oxide spinel compound and method of preparing same

ABSTRACT

The present invention includes lithium manganese oxide spinel compounds having a low porosity, a high tap density and a high pellet density, and methods of preparing these compounds. In particular, the method comprises preparing a lithium manganese oxide with a spinel structure and having the formula: wherein:  
         Li     1   +   x            Mn     2   -   Y            M     m   1     1          M     m   2     2        …                   M     m   k     k          O     4   +   Z                     
 
     M 1 , M 2 , . . . M k  are cations different than lithium or manganese selected from the group consisting of alkali earth metals, transition metals, B, Al, Si, Ga and Ge;  
     X, Y, m 1 , m 2 , . . . m k , each have a value between 0 and 0.2;  
     Z has a value between −0.1 and 0.2; and  
     X, Y, m 1 , M 2 . . . m k  are selected to satisfy the equation: 
     Y=X+ m   1   +m   2   +. . . +m   k .

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisionalapplication Ser. No. 60/104,396, filed Oct. 15, 1998, and U.S.Provisional Application Ser. No. 60/105,088, filed Oct. 21, 1998, under35 U.S.C. § 119(e).

FIELD OF THE INVENTION

[0002] This invention relates to lithiated metal oxide intercalationcompounds, and particularly to lithium manganese oxides with spinelstructures for positive electrodes in 4 V secondary lithium andlithium-ion batteries.

BACKGROUND OF THE INVENTION

[0003] Lithium manganese oxide spinel compounds such asLi_(1+X)+Mn_(2−X)O_(4+y) have been used as positive electrode materialfor 4 V secondary lithium and lithium-ion batteries. Typically, thesespinel compounds are formed by firing (calcining) a mixture of amanganese source compound and a lithium source compound. Exemplarymanganese source compounds include manganese carbonate (MnCO₃),electrochemical manganese dioxide (γ-Mn O₂ or EMD), and chemicalmanganese dioxide (γ-MnO₂ or CMD).

[0004] As described in coassigned U.S. Pat. No. 5,789,115, the meanparticle size and particle size distribution of these compounds and, inparticular, Li_(1+X)Mn_(2−X)O_(4+Y), is dependent on the mean particlesize and particle size distribution of the raw materials used to makethese compounds and specifically the manganese source compound. Inaddition to affecting the particle size and particle size distributionof the lithium manganese oxide, the morphology, e.g., density andporosity, of the manganese source compound can affect the morphology ofthe resulting lithium manganese oxides. In particular, the crystalgrowth of the spinel phase using a low density manganese compound causesan increase in the distance between the spinel crystallites and has anegative effect on the final density of the spinel compound. Thispresents a problem with MnCO₃ and CMD because these manganese sourcecompounds have relatively low densities and thus produce a low densityproduct. Because EMD has a higher density than MnCO₃ and CMD, EMD isoften used instead of these manganese source compounds to produce spinelcompounds. Nevertheless, the combined water, porosity and vacancies inthe EMD structure have a negative effect on the density of the resultingspinel compound.

[0005] The morphology of the manganese source compound also affects thetap and pellet density of the spinel compound. The tap and pelletdensity are important properties characterizing positive electrodematerials for secondary lithium and lithium-ion batteries. Inparticular, these properties directly influence the specific cellenergy, cell safety performance, manganese dissolution, capacity fadeand capacity loss at room and elevated temperatures, for theelectrochemical cell. Therefore, providing a method for preparinglithium manganese oxide spinel compounds having a desired tap and pelletdensity is of great importance in developing high energy density andhigh electrochemical performance 4 V secondary lithium and lithium ionbatteries.

SUMMARY OF THE INVENTION

[0006] The present invention is directed to lithium manganese oxidespinel compounds having a low porosity, a high tap density and a highpellet density, and a method of preparing these compounds. Inparticular, the method comprises preparing a lithium manganese oxidewith a spinel structure and having the formula:Li_(1 + x)Mn_(2 − Y)M_(m₁)¹M_(m₂)²…  M_(m_(k))^(k)O_(4 + Z)

[0007] wherein:

[0008] M¹, M², . . . M^(k) are cations different than lithium ormanganese selected from the group consisting of alkali earth metals,transition metals, B, Al, Si, Ga and Ge;

[0009] X, Y, m₁, m₂, . . . m_(k) are molar parts, each having a valuebetween 0 and 0.2;

[0010] Z is a molar part having a value between −0.1 and 0.2; and

[0011] the molar parts X, Y, m₁, m₂. . . m_(k) are selected to satisfythe equation:

Y=X+m ₁ +m ₂ +. . . +m _(k)

[0012] These lithium manganese oxide compounds are produced by calcininga mixture comprising at least one manganese oxide (manganese sourcecompound) selected from the group consisting of Mn₂O₃ or Mn₃O₄, at leastone lithium compound, and optionally at least one M¹, M², . . . M^(k)source compound, in at least one firing step at a temperature betweenabout 400° C. and about 900° C.

[0013] The manganese oxide compounds can be formed by firing highlycrystalline β-MnO₂ at a temperature between about 500° C. and 1000° C.Preferably, the β-MnO₂ is fired at a temperature between about 600° C.and about 800° C. in the preparing step to form Mn₂O₃ manganese oxide.The highly crystalline β-MnO₂ used to produce the Mn₂O₃ or Mn₃O₄ ispreferably formed by firing Mn(NO₃)₂ at a temperature between about 200°C. and about 400° C. to thermally decompose the Mn(NO₃)₂ and formβ-MnO₂. In addition, the β-MnO₂ preferably has a mean particle size ofbetween about 5 μm and about 20 μm and can be ground to produce thismean particle size.

[0014] In the calcining step, the mixture of source compounds is firedat between about 400° C. and about 900° C. Preferably, the mixture iscalcined using more than one firing step at firing temperatures withinthis temperature range. During calcination, agglomeration of the spinelparticles is preferably prevented. For example, during a multiple stepfiring sequence, agglomeration can be prevented by firing the sourcecompounds in a fluid bed furnace or rotary calciner during at least aportion of the firing steps or by grinding the spinel material betweensteps. The lithium manganese oxide spinel compounds of the invention canbe used as positive electrode material for a secondary lithium orlithium-ion electrochemical cell.

[0015] The lithium manganese oxide spinel compounds of the inventionhave a high tap density and pellet density and a low porosity andspecific area. In addition, these compounds have a high specificcapacity, low capacity fade during cycling, and a low capacity lossduring storage at room and elevated temperatures. In particular, thespinel compounds of the invention have a tap density of greater than 1.9g/cm³ and preferably greater than 2.1 g/cm³. The pellet density forthose spinel compounds is greater than 2.85 g/cm³, preferably greaterthan 2.90 g/cm³, or even greater than 2.95 g/cm³. The pore volume of thepores having a mean radius of less than 1 micron in the spinel compoundis no more than 20%, preferably no more than 15% or even no more than10%, of the total pore volume of the spinel compound, thus illustratingthe low porosity of the spinel compound. In addition, the specific areaof the spinel compound is less than about 0.8 m²/g and preferably lessthan 0.6 m²/g or even less than 0.5 m²/g.

[0016] The present invention also includes the Mn₂O₃ and Mn₃O₄ manganeseoxide compounds used to produce the spinel compounds of the invention.These manganese oxide compounds are highly crystalline and have a lowporosity. In particular, these manganese oxide compounds have a porositysuch that the pore volume of pores having a mean radius of less than 1micron in said manganese oxide is no more than 20% of the total porevolume of said manganese oxide. These manganese oxides also have aspecific area of less than 2.0 m²/g, preferably less than 1.5 m²/g oreven less than 1.0 m²/g. The tap density of the manganese oxides ispreferably greater than 2.2 g/cm³, more preferably greater than 2.4g/cm³.

[0017] These and other features and advantages of the present inventionwill become more readily apparent to those skilled in the art uponconsideration of the following detailed description and accompanyingdrawings which describe both the preferred and alternative embodimentsof the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] This invention may be better understood and its numerous objectsand advantages will become apparent to those skilled in the art byreference to the accompanying drawings and photographs as follows:

[0019]FIG. 1 is a graph of specific capacity v. charge-discharge cyclesfor Li_(1.04)Mn_(1.96)O₄ spinel compounds and compares the specificcapacity and cycleability of spinel compounds prepared directly fromβ-MnO₂ and prepared according to the present invention using a Mn₂O₃precursor obtained from β-MnO₂.

[0020]FIGS. 2A and 2B are SEM photographs of lithium manganese oxidespinel compounds prepared from a Mn₂O₃ precursor obtained from β-MnO₂according to the present invention and demonstrating the dense structureof the spinel compounds of the invention.

[0021]FIGS. 3A and 3B are scanning electron microscope (SEM) photographsof a spinel compound prepared from MnCO₃ by calcination at 825° C.

[0022]FIGS. 4A and 4B are SEM photographs of a spinel compound preparedfrom γ-MnO₂ (EMD) by calcination at 750° C.

[0023]FIG. 5 is a graph illustrating the integral porosity as a functionof pore radius of spinel compounds of the invention compared to theintegral porosity of spinel compounds produced from MnCO₃.

[0024]FIG. 6 is a graph of specific capacity v. charge-discharge cyclesillustrating the cycling performance (i.e. specific capacity andcycleability) at 1 hour and 10 hour charge-discharge rates forLi_(1.03)Mn_(1.96)Co_(0.01)O₄ spinel compounds prepared according to thepresent invention from a Mn₂O₃ precursor converted from β-MnO₂ at 600°C.

[0025]FIG. 7 is a graph of specific capacity v. charge-discharge cyclesillustrating the cycling performance (i.e. specific capacity andcycleability) at 1 hour and 10 hour charge-discharge rates forLi_(1.03)Mn_(1.96)Co_(0.01)O₄ spinel compounds prepared according to thepresent invention from a Mn₂O₃ precursor converted from β-MnO₂ at 650°C.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] As will be understood by those skilled in the art in reading thisapplication, the term “lithium manganese oxide” includes not onlycompounds that include only lithium, manganese and oxygen, but alsocompounds that include dopants such as alkali earth metals, transitionmetals, B, Al, Si, Ga and Ge.

[0027] It has been unexpectedly discovered in accordance with theinvention that using Mn₂O₃ or Mn₃O₄, preferably formed from β-MnO₂, toproduce lithium manganese oxide spinel compounds can produce spinelcompounds having good electrochemical performance and excellent pelletand tap densities. In particular, β-MnO₂, Mn₂O₃, and Mn₃O₄ are known inthe art as being chemically inactive with lithium salts. For example, asshown in FIG. 1, lithium manganese oxide spinels formed directly fromβ-MnO₂ have extremely poor electrochemical performance. However, it hasbeen discovered that by using highly crystalline Mn₂O₃ or Mn₃O₄prepared, e.g., using highly crystalline β-MnO₂, a high densitymanganese oxide can be obtained having a high chemical activity. Thehighly crystalline β-MnO₂ used in the invention is not porous and thushas a greater density than MnCO₃, CMD and EMD. Furthermore, the β-MnO₂has no combined water and has a highly ordered structure. Therefore, asshown in FIG. 1, using β-MnO₂ to form a manganese precursor for lithiummanganese oxide preparation leads to a product with dramatically betterelectrochemical performance than using β-MnO₂ directly.

[0028] As stated above, the β-MnO₂ preferably used to prepare the Mn₂O₃and Mn₃O₄ manganese oxides is a highly crystalline β-MnO₂. The highcrystallinity of the β-MnO₂ can be determined by measuring peak-widthsusing x-ray diffraction. An exemplary highly crystalline β-mnO₂ can beformed by firing Mn(NO₃)₂ at a temperature between about 200° C. andabout 400° C. to thermally decompose the Mn(NO₃)₂ and form β-MnO₂. Theβ-MnO₂ is fired at a temperature between about 500° C. and about 1000°C. to produce Mn₂O₃ or Mn₃O₄. Preferably, the β-MnO₂ is fired at atemperature between about 600° C. and about 800° C. to form Mn₂O₃. Inaddition, the β-MnO₂ is preferably fired for between about 1 hour and 10hours to produce these manganese oxides but can be fired for a longerperiod of time without negative effects. The β-MnO₂ preferably has amean particle size of between about 5 μm and 20 μm prior to forming themanganese oxides and can be ground to this mean particle size prior tofiring.

[0029] In one embodiment of the invention, the β-MnO₂ is fired at astarting temperature of about 500° C. and the temperature slowly raised(e.g. at a rate of less than about 1° C./min) to a final temperaturebetween about 600° C. and about 650° C. to thermally decompose theβ-MnO₂ to form Mn₂O₃. By slowly raising the temperature, a Mn₂O₃compound with an even better density and chemical activity is obtained.

[0030] The Mn₂O₃ or Mn₃O₄ manganese oxides resulting from firing β-MnO₂have a tap density of greater than 2.2 g/cm³, and preferably greaterthan 2.4 g/cm³. In addition, the particle size of the Mn₂O₃ or Mn₃O₄ istypically between about 1.1 and 1.3 times the size of the β-MnO₂, i.e.,between about 6 μm and 25 μm. The specific area of the Mn₂O₃ or Mn₃O₄ isless than 2.0 m²/g and preferably less than 1.5 m²/g, or even less than1.0 m²/g (as determined by one point BET). These manganese oxides alsopreferably have high crystallinity and low porosity. In particular, theporosity of these manganese oxides is preferably such that the porevolume of the pores having a mean radius of less than 1 micron is nomore than 20%, preferably no more than 15% or even no more than 10% ofthe total pore volume of the manganese oxide using Mercury porosimetry.In addition to using highly crystalline Mn₂O₃ or Mn₃O₄ formed fromβ-MnO₂, highly crystalline Mn₂O₃ or Mn₃O₄ prepared by other methods andhaving the above properties can also be used in the present invention.

[0031] The Mn₂O₃ or Mn₃O₄ is combined with lithium source compounds andoptionally dopant (M¹, M². . . M^(k)) source compounds to produce astoichiometric mixture according to the formula:Li_(1 + x)Mn_(2 − Y)M_(m₁)¹M_(m₂)²…  M_(m_(k))^(k)O_(4 + Z)

[0032] wherein:

[0033] M¹, M², . . . M^(k) are cations different than lithium ormanganese selected from the group consisting of alkali earth metals,transition metals, B, Al, Si, Ga and Ge;

[0034] X, Y, m₁, m₂, . . . m_(k) are molar parts, each having a valuebetween 0 and 0.2;

[0035] Z is a molar part having a value between −0.1 and 0.2; and

[0036] the molar parts X, Y, m₁, m₂, . . . m_(k) are selected to satisfythe equation:

Y=X+m ₁ +m ₂ +. . . +m _(k)

[0037] The lithium and dopant source compounds can be pure elements butare typically compounds containing the elements such as oxides or saltsthereof. In addition, the lithium and dopant cations can each besupplied from separate source compounds or two or more of the cationscan be supplied from the same source compounds. Preferably, the lithiumsource compounds include one or any combination of the following: LiOH,LiNO₃, Li₂CO₃, LiCl and LiF. The manganese oxide and lithium and dopantsource compounds can be mixed in any desirable order. In addition,although the spinel compounds are preferably prepared by solid statereactions, it can be advantageous to react the raw materials using wetchemistry alone or in combination with solid state reactions. Forexample, the reaction mixture can be prepared by suspending sourcecompounds in a solution of other source compounds and spray drying theresulting slurry to obtain an intimate mixture.

[0038] The mixture of the manganese oxide and lithium and dopant sourcecompounds can be calcined in a solid state reaction to form a lithiummanganese oxide with a spinel structure by firing the mixture in atleast one firing step at a temperature between about 400° C. and about900° C. in the presence of oxygen, e.g., in an atmosphere having anoxygen partial pressure of at least 10 kPa. Exemplary firing sequencesare disclosed, e.g., in coassigned U.S. Pat. Nos. 5,718,877 and5,792,442. Preferably, the mixture is calcined using more than onefiring step at firing temperatures between about 450° C. and 850° C. andfor a total firing time between about 4 and about 48 hours to form thespinel compounds. The mixture can also be fired for a longer period oftime without negatively affecting the resulting product. Once themixture has been fired to form the lithium manganese oxide spinelcompound, the resulting compound is preferably cooled to ambienttemperature in a controlled manner, e.g., at a rate of 1° C./min orless.

[0039] It has been discovered that agglomeration of the spinel particlesoccurs during spinel phase nucleation in the calcination step, e.g.,during the initial firing step of a multiple step firing sequence. Thisagglomeration is preferably prevented by suitable means to producespinel particles having a mean particle size between about 7 μm andabout 30 μm. For example, agglomeration can be prevented by firing themixture during at least the initial firing steps in a fluid bed furnaceor rotary calciner to minimize the contact between the particles in themixture. The spinel particles can also be ground to the desired particlesize between firing steps, especially between the initial firing steps,to prevent agglomeration.

[0040] The resulting lithium manganese oxide spinel compounds have hightap and pellet densities. Preferably, these tap and pellet densities canbe improved by mildly dispersing the resulting lithium manganese oxidespinel compounds in an unreactive solvent such as acetone.Alternatively, the spinel compound can be dispersed in a dry mixture byplacing the compound in a mixer for a short period of time, e.g., 1 to60 minutes.

[0041] The present invention also includes a lithium manganese oxidespinel compound having the formula:Li_(1 + x)Mn_(2 − Y)M_(m₁)¹M_(m₂)²…  M_(m_(k))^(k)O_(4 + Z)

[0042] wherein:

[0043] M¹, M², . . . M^(k) are cations different than lithium ormanganese selected from the group consisting of alkali earth metals,transition metals, B, Al, Si, Ga and Ge;

[0044] X, Y, m₁, m₂, . . . m_(k) are molar parts, each having a valuebetween 0 and 0.2;

[0045] Z is a molar part having a value between −0.1 and 0.2; and

[0046] the molar parts X, Y, m₁, m₂, . . . m_(k) are selected to satisfythe equation:

Y=X+m ₁ +m ₂ +. . . +m _(k)

[0047] As shown in FIGS. 2A and 2B, the spinel compounds of theinvention have low porosity and high density, especially compared tospinel compounds prepared from MnCO₃ (FIGS. 3A and 3B) and EMD (FIGS. 4Aand 4B). In addition, FIG. 5 illustrates that the porosity of a spinelcompound prepared according to the invention is significantly lower thanthe porosity of a spinel compound prepared from MnCO₃ as measured usingMercury porosimetry. In particular, FIG. 5 illustrates that the poresize and pore size distribution of a spinel compound prepared accordingto the invention is such that the pore volume of pores having a meanradius of less than 1 micron is about 10% of the pore volume of thespinel compound. The pore size and pore size distribution of a spinelcompound prepared from MnCO₃, on the other hand, is such that the porevolume of the pores with a mean radius of less than 1 micron is about45% of the total pore volume of the spinel compound. Because the volumeof micropores (pores of less than 1 micron between the crystalliteswithin the particles) is significantly less than the volume ofmacropores (pores of greater than 1 micron between the particles), thespinel compounds of the invention have a low porosity and thus have ahigh tap and pellet density compared, e.g., to spinel compounds preparedfrom MnCO₃.

[0048] Specifically, the spinel compounds of the invention have a tapdensity of greater than 1.9 g/cm³, preferably greater than 2.1 g/cm³. Inaddition, the spinel compounds of the invention preferably have a pelletdensity of greater than about 2.85 g/cm³ and more preferably greaterthan 2.90 g/cm³, or even greater than 2.95 g/cm³. As is understood bythose skilled in the art, the tap density is measured according to themethod described in detail in the Handbook of Manganese Dioxides (1989)published by the International Battery Material Association. The pelletdensity is the measured density at 20,000 psi.

[0049] In addition to these properties, the porosity of the spinelcompounds of the invention is such that the pore volume of the poreshaving a mean radius of less than 1 micron is no more than 20% andpreferably no more than 15% or even no more than 10%, of the total porevolume of the spinel compound using Mercury porosimetry. These compoundsalso have a specific area of less than about 0.8 m²/g, preferably lessthan about 0.6 m²/g, or even less than about 0.5 m²/g using a one pointBET method. The mean particle size of the spinel compound of theinvention is preferably between 7 μm and 30 μm. These compounds also aresingle phase compounds and preferably have a full width at half maximumof x-ray diffraction peaks from planes (400) and (440) using CuKα raysof less than about 0.15° 2θ, and more preferably less than or equal to0.125° 2θ.

[0050] In addition to the advantageous physical characteristics of thespinel compounds of the invention, these compounds also exhibit superiorelectrical performance. Specific capacities and cycleabilities for thesecompounds are illustrated in FIGS. 6 and 7.

[0051] In particular, these compounds have a capacity fade at roomtemperature between cycles 1-50 of preferably less than about 12%, andmore preferably less than about 10%. Moreover, the capacity fade at roomtemperature for the compounds of the present invention between cycles100-200 is preferably less than about 6%, more preferably less thanabout 5%.

[0052] The lithium manganese oxide spinel compounds of the inventionpossess the properties desired in the art including a desired metaloxide composition, structure, density and electrochemical performance.The spinel compounds prepared according to the present invention alsohave high tap and pellet densities. In addition, these spinel compoundshave a predetermined mean particle size, particle size distribution, andhigh gravimetric specific energy. These spinel compounds can be used inthe positive electrodes of secondary lithium and lithium ion cells toprovide cells having high specific energy, safety cell performance, lowmanganese dissolution, low capacity fade during cycling and low capacityloss during storage at room and elevated temperatures.

[0053] It is understood that upon reading the above description of thepresent invention and reviewing the accompanying drawings, one skilledin the art could make changes and variations therefrom. These changesand variations are included in the spirit and scope of the followingappended claims.

That which is claimed:
 1. A lithium manganese oxide with a spinelstructure and having the formula:Li_(1 + x)Mn_(2 − Y)M_(m₁)¹M_(m₂)²…  M_(m_(k))^(k)O_(4 + Z)

wherein: M¹, M², . . . M^(k) are cations different than lithium ormanganese selected from the group consisting of alkali earth metals,transition metals, B, Al, Si, Ga and Ge; X, Y, m₁, m₂, . . . m_(k), eachhave a value between 0 and 0.2; Z has a value between −0.1 and 0.2; andX, Y, m₁, m₂, . . . m_(k) are selected to satisfy the equation: Y=X+m ₁+m ₂ +. . . +m _(k) and wherein the pore volume of pores having a meanradius of less than 1 micron in said lithium manganese oxide is no morethan 20% of the total pore volume of said lithium manganese oxide. 2.The spinel compound according to claim 1 wherein the pore volume ofpores having a mean radius of less than 1 micron is no more than 15% ofthe total pore volume of said lithium manganese oxide.
 3. The spinelcompound according to claim 1 wherein the pore volume of pores having amean radius of less than 1 micron is no more than 10% of the total porevolume of said lithium manganese oxide.
 4. The spinel compound accordingto claim 1 wherein the pellet density is greater than 2.85 g/cm³.
 5. Thespinel compound according to claim 1 wherein the pellet density isgreater than 2.90 g/cm³.
 6. The spinel compound according to claim 1wherein the pellet density is greater than 2.95 g/cm³.
 7. The spinelcompound according to claim 1 wherein the tap density is greater than1.9 g/cm³.
 8. The spinel compound according to claim 1 wherein the tapdensity is greater than 2.1 g/cm³.
 9. The spinel compound according toclaim 1 wherein the specific area is less than 0.8 m²/g.
 10. The spinelcompound according to claim 1 wherein the specific area is less than 0.6m²/g.
 11. The spinel compound according to claim 1 wherein the specificarea is less than 0.5 m²/g.
 12. The spinel compound according to claim 1wherein said cations M¹, M², . . . , M^(k) include cobalt.
 13. A highlycrystalline Mn₂O₃ or Mn₃O₄ manganese oxide having a specific area ofless than 2.0 m²/g and a low porosity such that the pore volume of poreshaving a mean radius of less than 1 micron in said manganese oxide is nomore than 20% of the total pore volume of said manganese oxide.
 14. Themanganese oxide of claim 13 wherein the specific area is less than 1.5m²/g.
 15. The manganese oxide of claim 13 wherein the specific area isless than 1.0 m²/g.
 16. The manganese oxide of claim 13 further having atap density of greater than 2.2 g/cm³.
 17. The manganese oxide of claim13 further having a tap density of greater than 2.4 g/cm³.
 18. A methodof preparing a lithium manganese oxide with a spinel structure andhaving the formula:Li_(1 + x)Mn_(2 − Y)M_(m₁)¹M_(m₂)²…  M_(m_(k))^(k)O_(4 + Z)

wherein: M¹, M², . . . M^(k) are cations different than lithium ormanganese selected from the group consisting of alkali earth metals,transition metals, B, Al, Si, Ga and Ge; X, Y, m₁, m₂, . . . , m_(k),each have a value between 0 and 0.2; Z has a value between −0.1 and 0.2;and X, Y, m₁, m₂, . . . m_(k) are selected to satisfy the Y=X+m ₁ +m ₂+. . . +m _(k) equation: said method comprising the step of: calcining amixture comprising: at least one highly crystalline manganese oxideselected from the group consisting of Mn₂O₃ and Mn₃O₄, said manganeseoxide having a specific area of less than 2.0 m²/g and a low porositysuch that the pore volume of pores having a mean radius of less than 1micron in said manganese oxide is no more than 20% of the total porevolume of said manganese oxide; and at least one lithium sourcecompound; in at least one firing step at a temperature between about400° C. and about 900° C. to form the lithium manganese oxide spinelcompound.
 19. The method according to claim 18 wherein said calciningstep comprises calcining said at least one manganese oxide, said atleast one lithium source compound, and at least one M¹, M², . . . M^(k)source compound.
 20. The method according to claim 18 wherein saidcalcining step comprises calcining a mixture wherein the manganese oxidehas a specific area of less than 1.5 m²/g.
 21. The method according toclaim 18 wherein said calcining step comprises calcining a mixturewherein the manganese oxide has a specific area of less than 1.0 m²/g.22. The method according to claim 18 wherein said calcining stepcomprises calcining a mixture wherein the manganese oxide has a tapdensity of greater than 2.2 g/cm³.
 23. The method according to claim 18wherein said calcining step comprises calcining a mixture wherein themanganese oxide has a tap density of greater than 2.4 g/cm³.
 24. Amethod of preparing a lithium manganese oxide with a spinel structureand having the formula:Li_(1 + x)Mn_(2 − Y)M_(m₁)¹M_(m₂)²…  M_(m_(k))^(k)O_(4 + Z)

wherein: M¹, M², . . . , M^(k) are cations different than lithium ormanganese selected from the group consisting of alkali earth metals,transition metals, B, Al, Si, Ga and Ge; X, Y, m₁, m₂, . . . , m_(k),each have a value between 0 and 0.2; Z has a value between −0.1 and 0.2;and X, Y, m₁, M₂, . . . m_(k) are selected to satisfy the equation:Y=X+m ₁ +m ₂ +. . . +m _(k) said method comprising the steps of:preparing at least one manganese oxide selected from the groupconsisting of Mn₂O₃ and Mn₃O₄ by firing β-MnO₂ at a temperature betweenabout 500° C. and about 1000° C.; and calcining a mixture comprisingsaid manganese oxide and at least one lithium source compound in atleast one firing step at a temperature between about 400° C. and about900° C. to form the lithium manganese oxide spinel compound.
 25. Themethod according to claim 24 wherein said calcining step comprisescalcining a mixture of said manganese oxide, said at least one lithiumsource compound, and at least one M¹, M², . . . , M^(k) source compound.26. The method according to claim 24 , wherein said preparing stepcomprises firing β-MnO₂ at a temperature between about 600° C. and about800° C. to form Mn₂O₃.
 27. The method according to claim 24 wherein saidpreparing step comprises firing the β-MnO₂ at a starting temperature ofabout 500° C. and raising the temperature at a rate of less than 1°C./min to a temperature between about 600° C. and about 650° C. tothermally decompose the β-MnO₂ and form Mn₂O₃.
 28. The method accordingto claim 24 , further comprising the step of firing Mn(NO₃)₂ at atemperature between about 200° C. and about 400° C. to thermallydecompose the Mn(NO₃)₂ and form β-MnO₂ prior to said preparing step. 29.The method according to claim 24 , wherein said preparing step comprisesfiring β-MnO₂ having a mean particle size between about 5 μm and about20 μm.
 30. The method according to claim 29 , wherein said preparingstep further comprises grinding the β-MnO₂ to between about 5 μm andabout 20 μm prior to said firing the β-MnO₂.
 31. The method according toclaim 24 , further comprising the step of mildly dispersing the lithiummanganese oxide spinel compound after said calcining step.
 32. Themethod according to claim 24 , wherein said calcining step comprisesfiring the mixture in more than one firing step at firing temperaturesbetween about 450° C. and about 850° C.
 33. The method according toclaim 24 , further comprising the step of preventing agglomeration ofthe spinel compounds during at least a portion of said calcining step.34. The method according to claim 33 , wherein at least a portion ofsaid calcining step comprises calcining the mixture in a fluid bedfurnace or rotary calciner.
 35. The method according to claim 33 ,wherein said calcining step comprises grinding the resulting spinelcompound during at least a portion of said calcining step.
 36. A lithiummanganese oxide with a spinel structure and having the formula:Li_(1 + x)Mn_(2 − Y)M_(m₁)¹M_(m₂)²…  M_(m_(k))^(k)O_(4 + Z)

wherein: M¹, M², . . . M^(k) are cations different than lithium ormanganese selected from the group consisting of alkali earth metals,transition metals, B, Al, Si, Ga and Ge; X, Y, m₁, m₂, . . . m_(k), eachhave a value between 0 and 0.2; Z has a value between −0.1 and 0.2; andX, Y, m₁, m₂, . . . m_(k) are selected to satisfy the equation: Y=X+m ₁+m ₂ +. . . +m _(k) and wherein the tap density is greater than 1.9g/cm³, the pellet density is greater than about 2.85 g/cm³, the specificarea is less than 0.8 m²/g, and the full width at half maximum of x-raydiffraction peaks from planes (400) and (440) using CuKα rays is lessthan about 0.15° 2θ.
 37. The spinel compound according to claim 36 ,wherein the tap density is greater than 2.1 g/cm³.
 38. The spinelcompound according to claim 36 , wherein the specific area is less than0.6 m²/g.
 39. The spinel compound according to claim 36 , wherein thespecific area is less than 0.5 m²/g.
 40. The spinel compound accordingto claim 36 , wherein the full width at half maximum of x-raydiffraction peaks from planes (400) and (440) using CuKα rays is lessthan about 0.125° 2θ.